Recent work with electrical stimulation in this laboratory has resulted in a detailed map of rat brainstem. Species typical behaviors which have been elicited are attack, eating, drinking, gnawing and grooming. With this information in hand the objective is to lesion these mid brain and pontine areas and determine their effects of hypothalamically elicited behavior. The effect of hypothalamic lesions on behavior elicited from the brainstem shall also be determined. Concurrently a project concerned with chemical stimulation of lower brainstem structures will be continued and expanded. Pilot work in this laboratory has indicated that cholinergic substances when injected directly into the mid brain and pons elicits eating, drinking and attack. Determination of dose-response relationships in these and other effective brainstem sites is an immediate goal. Chemical blockade of natural and elicited species typical behavior will also be studied.